Offshore wind park

ABSTRACT

The present invention relates to wind farms, so called, comprising at least two wind turbines, and in particular to offshore wind farms. In order to provide a wind farm in which transport between separate wind turbines can be effected more safely and with less dependence on weather, at least one cable connection is provided between at least two of the wind turbines of a wind farm, and a vessel is disposed on said cable connection.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a wind farm comprising at least twowind turbines and in particular to an offshore wind farm.

2. Description of the Related Art

The wind turbines in wind farms are spaced from one another at suchdistances that any collision of blades is securely avoided even when thewind turns direction, and the effects of one wind turbine on another asa result of changing air flow conditions are kept as small as possible.The distance between wind turbines is dependent on the radius of thecircle swept by the rotor of a wind turbine and, with rotor diameters inexcess of 100 m now possible at the current state of technologicaldevelopment, the distance between wind turbines will increase stillfurther due to the even larger dimensions of new wind turbines.

Depending on location and size, each wind turbine requires maintenanceand the elimination of any malfunctions that may arise. To do this,personnel and material must be transported to the wind turbine.

It is relatively easy to bring personnel and material to every windturbine on land-based wind farms, whereas in the case of offshore windfarms this involves much greater effort and expense. The process can besimplified by bringing people and goods, such as tools, spare parts,etc. to one place only, rather than having to call at each separate windturbine on a wind farm.

The problem which then arises is that of distributing landed goods, orgenerally of transporting goods and/or people between the wind turbinesof a wind farm, and particularly of an offshore wind farm.

Based on the premise that a wind farm has a central landing place whereall goods and persons arrive or depart, the latter must accordingly betransported between the separate wind turbines of the wind farm.

One characteristic of offshore wind farms is that the weather there isalways rougher than on land. Winds can blow unobstructed and quicklyreach high speeds.

Furthermore, waves of greater or lesser height must be expected at alltimes. Therefore, transporting goods and ferrying people to the separatewind turbines is not only unpleasant in many cases, but may even involvea considerable degree of risk, and at high wind forces is practicallyimpossible.

BRIEF SUMMARY OF THE INVENTION

One object of the present invention is therefore to provide a wind farmin which the separate wind turbines of the wind farm can be reliablyserviced, and in which such servicing can still be performed even whenrough weather conditions prevail for several days.

This object is achieved according to the invention with a wind farmhaving the features of claim 1. Advantageous embodiments are describedin the subclaims.

The wind farm according to the invention comprises not only a pluralityof wind turbines, but also has a separate offshore platform on whichpeople responsible for servicing the wind farm can live and work. Suchan offshore platform must presumably be equipped in such a way thatpersons staying there can also remain and take care of themselves therefor several weeks at a time. This requires, therefore, that the offshoreplatform be fitted with appropriate “social” facilities, i.e., sleepingquarters, mess rooms, kitchen, recreation rooms, etc.

If, at higher wind forces, operating personnel has to cross to oneturbine or the other in order to carry out maintenance or servicing,said wind turbines can preferably be reached via the cableway connectionrunning from the platform. This obviates the need for any kind oftransportation by ship or helicopter, while also enabling themaintenance and servicing material to be transported at the same timevia the cableway connection.

In another embodiment of the invention, the platform can also beequipped with an electrolysis plant so that water can be converted toits hydrogen and oxygen constituents using the electricity generated bythe wind turbine. The hydrogen produced in this way, and preferably alsothe oxygen, is stored in appropriate gas tanks (on the platform) and canthen be transported to land by ship or pipeline.

In certain circumstances, such production of hydrogen and oxygen canmake particular sense if fuel cell drives for vehicles becomeestablished, because in such a case there will be a very high demand forhydrogen, which can be generated on the high seas with the invention,without said production posing a hazard in any way for facilities onland, such as buildings, residential areas, etc.

If necessary, it is possible to provide several platforms instead ofjust one, in such a way that, in addition to a residential platform,there is also a “hydrogen production platform”. In the event of anaccident on the production platform, the personnel still has the chanceto withdraw to the safety of the residential platform.

In such a case, the separate platforms should, of course, be connectedto each other with a suitable cableway connection.

The cableway connection is usually fitted with a motoric drive. Forsafety reasons, it is also advantageous if cableway transport is stillpossible when a power failure has occurred. Such a manual drive could beprovided in the form of suitable facilities that can be operated withhuman power.

In the cableway or cable connection, the cable is preferably spanned atsuch a height that it neither impinges on the rotor diameter of the windturbine nor touches the crests of waves, such than ships are unable tocollide with the cable connections even when the waves are high.

A deflection member for the cable connection can be provided on eachwind turbine and on each platform, such that the cable connection isspanned as an endless cable loop between the deflection members and thegondola is fixedly connected to the cable connection. By this means, thegondola can be driven in the desired direction by moving the cableconnection, and the structure is kept very simple.

When there are two wind turbines connected to each other, the cableconnection travels around the deflection member at each wind turbine andback to the other wind turbine.

When the cable connection connects at least three wind turbines witheach, the deflection member on the middle wind turbine serves as asupport, and the cable connection is guided onwards to the respectiveouter wind turbine.

The cable connection can be moved by means of a motor, and preferably byan electrically driven motor. This is particularly advantageous, becauseelectrical energy is generated in the wind farm and is therefore readilyavailable, thus obviating the need to transport other energy carriers,such as fuel. Electric motors can also be controlled in a simple manner.

The cable connection suitably comprises a main cable and a tractioncable. Although the gondola is mounted on the main cable, it is able totravel in relation to said main cable. The traction cable is attached tothe gondola. When the traction cable is pulled in the desired directionof travel, the gondola moves along the main cable in the desireddirection. This traction on the traction cable can be provided by amotor. Electrical energy is advantageously used as the drive energy.

The deflection member preferably comprises two independently rotatabledeflection pulleys, whereby the main cable is guided over one roller andthe traction cable over the other roller. The traction cable can beconfigured as a circulating endless cable loop, whereas the main cablecan be provided only once along the stretch travelled by the gondola.Due to the endless traction cable, it is sufficient to have a reversibledrive for the traction cable in order to drive the gondola in thedesired direction, and one can dispense with any reeling devices for thetraction cable at the two ends thereof.

In one particularly preferred embodiment of the invention, the gondolamoves along the main cable under its own power. A motoric drive andpreferably an electromotoric drive can be provided for this purpose,whereby the store of energy for driving the motor is provided in anenergy storage means in the gondola, for example in an accumulator.

A manual drive may be provided as an alternative to the motoric drive,or as a supplementary emergency drive so that the gondola can be movedin emergency operation even when there is a failure of the motor or theenergy store.

In a particularly preferred embodiment of the invention, the driveenergy is supplied via the cable connection, the main cable, thetraction cable and/or a separate conductor line when the gondola isdriven electrically. By this means, control signals can also betransmitted to the gondola and/or a tower by remote control, for exampleto control the drive motor or a winch or the like.

In a preferred development of the invention, telematics data, forexample, are transmitted via the electrical connection to a centralfacility or to several wind turbines. Furthermore, it is possible viathe cable connection to process the communications, with each other andwith the gondola, of all the wind turbines in the wind farm betweenwhich the cable car is provided.

In an alternative embodiment of the invention, these communications,that is to say, for example, the transmission of telematics data,control signals, etc. between separate wind turbines on the wind farmand/or the gondola, can be effected at least in part by wirelesstransmission.

The cable connection can be structured in different ways. A simplestructure is based on the principle of a chain, in which all windturbines are connected to each other by the cable connection “like beadson a chain”. In this structure, the cable connection is a singlecontinuous cable connection that connects at least some of the windturbines in a predefinable series with each other.

However, the wind turbines may also be positioned in several rows, forexample in three rows, and the cable connection follows, for example, apath in the shape of the letter “S” between the wind turbines to connectthe wind turbines with each other.

An alternative variant of the cable system is a star-shaped arrangementof the cable connection, starting from a central facility representing,for example, a central landing place, so that all other wind turbinescan be reached by the shortest possible path.

Another variant is a networked cable system that not only providesshortest possible connections from a central wind turbine to the otherwind turbines, but also forms relatively short stretches between all thewind turbines.

In order to keep the horizontal displacement of the gondola on the cableconnection low while the gondola is travelling between the wind turbinesof a wind farm, or to prevent such displacement within certain limits,the wind farm according to the invention has, in a preferreddevelopment, a holding cable that is provided at a predefined verticaldistance parallel to the cable connection. The distance is dimensionedin such a way that the gondola is guided between the cable connectionand the holding cable. In this arrangement, the cable connection ispreferably above the gondola, and the holding cable is below thegondola.

In a particularly advantageous development of the invention, one (upper)part of the endless cable loop in a cable connection configured as anendless loop can carry the gondola, while the other (lower) part of theendless cable loop performs the function of the holding cable.

In an alternative embodiment, a flywheel mass rotating about a verticalaxis is used to stabilize the gondola. Said flywheel mass is driven by amotor and acts as a gyroscope to counter any horizontal displacement ofthe gondola.

Preferably, each wind turbine of the wind farm has a closeable door inits tower. Said door is generally located at the height at which thegondola reaches the wind turbine. This enables loading activities to beperformed without having to overcome a difference in height.

In another preferred development, the wind turbines and the gondola havea locking device that permits the loading and unloading position of thegondola to be prescribed, such that swinging movements of the gondolarelative to the tower of the wind turbine are prevented when the gondolais in said position. The locking device is preferably configured in sucha way that one part of the locking device is provided close to the dooron the tower of the wind turbine, and the other part at a suitableposition on the gondola. A particularly preferred embodiment is one inwhich the locking device is a two-point locking device, in order toavoid the formation of a pivotal point that occurs when locking operatesat one point only.

Preferably, said locking device can function electromagnetically and beswitched on and off by operating a switch inside the tower and/or fromthe gondola. This enables convenient and secure handling without therisk of injury as a result of a swinging gondola that may, for example,collide with the tower due to wind action.

In one preferred development of the invention, the locking device can beremotely controlled, and it is particularly preferred for it to beremotely controllable from the gondola so that manual operation can beavoided. By this means, the latent risk of injury when operating thelocking device is further reduced.

A particularly preferred embodiment is one in which a cover ofsubstantially horizontal extension is mounted above the opening on atleast one wind turbine, said cover bearing a protective wall extendingsubstantially vertically and at a predefined distance parallel to thecable connection. By means of the cover and the protective wall, whichenclose a predefined angle, a protective roof is formed that protectsthe gondola when in the area of the opening as well as the openingitself against weather. The gondola and the opening are protected by thetower itself, on the one hand, and by the protective roof, on the other,such that the gondola is shielded against the wind and is not pushedagainst the tower.

If the protective roof is made long enough, displacement of the gondolaand hence a potential collision with the tower can be avoided even whenthe wind or wind vectors are transverse to the direction in which thegondola is travelling.

The horizontal spacing between the outer ends of the first protectivewall and the tower is preferably greater than the horizontal spacing tothe central portion of the protective wall. In this way, collisionsbetween the gondola and the protective wall are prevented even when thegondola is horizontally displaced towards the protective wall, forexample by cross winds.

In one preferred development of the invention, additional protectivewalls can be attached to the tower on both sides of the opening parallelto the first protective wall and at the same height, said additionalwalls extending the area in lee of the tower such that a wind vectortransverse to the direction in which the gondola is travelling does notpush the latter against the outer protective wall. The horizontaldistance between the protective walls at the tower can be substantiallyequal to the width of the gondola and enlarge towards the lateral endsof the protective walls, such that a horizontal displacement of thegondola in the entry area between the protective walls does not lead tocollisions between the gondola and one of the protective walls.

The gondola itself can preferably be fitted with elastic coating at eachof the corners on the lower portion of the gondola cabin, and hence atthose points that will be affected first in the event that a collisionwith other facilities of the wind farm occurs as a result of the gondolabeing horizontally displaced. On the one hand, said coatings dampen anycollision that might occur, thus preventing damage occurring to thegondola and other facilities of the wind farm, and on the other handthey serve as buoyancy aids to keep the gondola buoyant in the event ofan accident.

At the same time as, or in place of the elastic coating on the gondola,such a coating may also be provided on the protective walls, especiallyin the entry area and at a height at which a horizontally displacedgondola first collides with the protective wall.

A particularly preferred embodiment is one in which a first gangboard isprovided at the second protective wall, said gangboard having aretention facility, such as a railing, all around it. In oneadvantageous development of the invention, the gangboard extends overthe entire length of the protective wall and is attached in such a waythat it can be reached from the opening.

By this means, the outer side of the gondola can be reached in order toperform repair work and/or maintenance and cleaning work, for example.If the second protective wall is present, the gangboard can bedelineated on one side by said protective wall, and a retention facilitycan be dispensed with there.

It is particularly preferred to provide a second gangboard parallel tothe first on the first protective wall. Said second gangboard, too, hasa retention facility on the sides which are not adjacent to the firstprotective wall.

As a further preferred embodiment, a transverse gangboard can beprovided at at least one outer end of the first and second gangboards,wherein said transverse gangboard bridges the gap between thesubstantially parallel first and second gangboards.

To enable unobstructed entry and exit of the gondola, the transversegangboard can be pivotably coupled at one of its ends and pivotedupwards about its pivot axis in order to clear the way for the gondolato pass through. In one advantageous development of the invention, suchtransverse pivotable gangboards are coupled at both ends of the first orthe second gangboard, thus enabling all sides of the gondola to bereached from the outside.

The gap between one transverse gangboard and the other is preferablyselected so that it is substantially equal to the relevant dimensions ofthe gondola. In one particularly preferred development of the invention,at least one of the transverse gangboards is slideable along its pivotalaxis, such that the distance between the transverse gangboards can bealtered and hence adjusted to the respective requirements.

On at least one wind turbine tower, a hoisting apparatus can beprovided, preferably under the protective roof, said hoisting deviceenabling the handling of heavy freight, on the one hand, and, on theother hand, the handling of the gondola and gondola parts, for examplefor repairs. By means of such a hoisting apparatus, provided it isdesigned for an appropriate load, the entire gondola can be hoisted sothat the underside of the gondola can be reached from the gangboard forrepair, maintenance and cleaning purposes.

In one alternative embodiment of the invention, a suitably mountedsingle- or multi-part working platform can be provided in place ofgangboards in order to reach the outer sides of the gondola. To thisend, the area of the working platform can have a minimum size thatenables all sides of the gondola to be accessed from the outside.

In another alternative embodiment of the invention, a working cage or acrown safety platform can be provided, wherein said cage or platform canbe moved and/or pivoted such that the outer sides of the gondola can bereached. The crown safety platform, like the working platform, isenclosed on all sides by a retention facility in order to prevent anyunintentional fall from the platform or cage on the part of personnelworking thereon.

In one particularly preferred embodiment of the invention, the door islarger than the cross section of the gondola, and the cable systemextends into the tower of the wind turbine. This is achieved by havingat least one set of points at each tower along the cable connection. Inthis way, the gondola can travel through the opened door in the towerand be loaded and/or unloaded therein regardless of weather conditions.

A closed gondola provides for transportation of people and goods in sucha manner that they are substantially protected against the weather. Inone particularly preferred development of the invention, the gondola isconfigured so that it has a closeable exit opening through which theguide with which the gondola is suspended from the cable connection andguided can be reached.

In order to avoid the loss of the gondola in the event of it fallingfrom the cable, the gondola is preferably designed to be buoyant, andcan dispose of signalling means such as signal guns, flares or the like,as well as buoyancy aids such as automatic self-inflating float rings.These buoyancy aids increase the buoyancy of the gondola so that itremains buoyant even when loaded. In one preferred development of theinvention, the gondola has righting aids that at least make it moredifficult for the gondola to overturn, or indeed prevent it from doingso.

In order to effect monitoring of operation, or at least semi-automaticcontrol of the cable car system, a central control device as well as aplurality of sensors and/or actuators are provided. The sensors and/oractuators can be connected to the central control device via aninterface.

By means of sensors connected thereto, the central control device canthus identify, on the one hand, certain operating parameters and states,for instance the position of the gondola, its operating speed, thehorizontal displacement, the weight of the gondola, the rotational speedof a flywheel mass, the amount of energy stored, motor operational data,the openings in the towers (closed, open, . . . ), etc. Of course,telematics data can also be captured by sensors in the machine house ofa wind turbine and subsequently processed.

By means of the actuators provided, the central control unit is able toinfluence operating parameters and states. This can involve, forexample, controlling the locking device between the gondola and thetower, depending on the position of the gondola relative to the tower,or controlling the lighting under the protective roof, or controllingposition lights (insofar as any are provided on the towers and/or otherparts of the wind farm) depending on brightness, or automaticallyreleasing or operating doors, or influencing the speed of the gondola,including bringing it to a stop.

In one alternative embodiment of the invention, the control system canbe decentralised. To this end, separate control systems can be providedin at least two of the facilities on a wind farm, said systemscommunicating with each other and with the gondola. In this way,operating parameters and states can likewise be identified and analysed.Each control system can be connected with a predefinable portion of thesensors and/or actuators. One advantage of this decentralised solutionis the redundancy thus provided, such that in the event of a controlunit failure, neighbouring control units can take over its functions.

In one particularly advantageous development of the invention, supportmasts are provided between wind turbines on a wind farm in order tosupport the cable connection and in this way prevent excessive sag ofthe cable connection between the towers, as well as the loads that canensue as a result of large spans between the towers of the wind turbineson a wind farm.

The wind farm according to the invention is preferably equipped with atleast one accommodation area for accommodating at least one person. Thespace within said accommodation area is preferably organised intodifferent functional areas, such as a sanitation area and/or a kitchenarea and/or a pantry area and/or a rest area, and it is particularlypreferable that it be integrated into the tower of a wind turbine.

In one alternative embodiment of the invention, the accommodation areais located separately from the wind turbines but within the wind farm.This location can be a separate platform, for example, or can preferablybe on a platform mounted on a tower of a wind turbine.

Said platform can serve additional functions, such as those of ahelicopter pad and/or a ship's berth.

Due to the limited area inside the tower, the accommodation area in apreferred development of the invention is distributed among severalinterconnected levels inside the tower. Within the accommodation area,equipment for communicating and signalling predefined data is provided.Said signalling may include acoustic and optical signalling, or anappropriate way of recording the data.

Communication includes voice and/or data communication on wire orwireless communication links, on the one hand with remote stationsoutside the wind farm, such as remote operations or maintenance centres,and on the other hand with remote stations inside the wind farm, such asother wind turbines or the gondola of the cable car system.

In a particularly preferred embodiment of the invention, communicationalso includes influencing predefined operating parameters of the windfarm facilities, as well as surveillance and control of wind farmoperation. By this means, a continuously manned monitoring station canbe created on the wind farm according to the invention, said monitoringstation being able to respond immediately in the event of faults orfailures occurring, and can take or initiate appropriatecounter-measures.

In one particularly preferred development of the invention, a watertreatment plant for supplying the personnel with drinking water andservice water is provided, said plant being operated with electricalenergy generated on the wind farm. To bridge gaps in supply due, forexample, to windless conditions, a suitably dimensioned energy storagemeans is provided to ensure that emergency operations at least aremaintained in order to continue supplying the accommodation area withenergy and water.

The energy storage means used for this purpose can be storage means forelectrical power, such as capacitors, chemical means of energy storage,such as accumulators, or storage means for hydrogen which are chargedwith hydrogen obtained from seawater by electrolysis, and from whichelectrical energy can be obtained in a fuel cell.

In one particularly preferred embodiment of the invention, at least thewind turbine equipped with the accommodation area includes equipment forweather observation, and/or for detecting, analysing, recording and/orforwarding meteorological data. Furthermore, the wind turbine oradditional (all) wind turbines in the wind farm can perform functions asnavigational aids for shipping, for example in the form of a sea markeror as a station for providing (first) aid to persons involved inaccidents, or to shipwrecked persons.

In one development of the invention, at least one wind turbine equippedwith an accommodation area has a viewing platform provided on the towerof the wind turbine below the machine house. Said viewing platform canencircle the tower of the wind turbine either completely, or at leastpartially in a preferred direction, and be fitted with windows thatenable the surrounding area to be monitored. Said viewing platform canalso be equipped with devices for signalling data, for influencingpredefined operating parameters and/or for communication. The windturbine with the viewing platform is positioned within the wind farm insuch a way that a maximum number (preferably all) of the wind turbinesin the wind farm can be seen from that position.

The viewing platform can be provided in close physical proximity to theaccommodation area, or form an integral part thereof. Alternatively, theviewing platform and the accommodation area can be spatially separated,with the accommodation area located below the viewing platform near thebase of the tower in order to permit more generous dimensions of therooms, whereas the viewing platform is located immediately below themachine house to enable good observation of the surroundings.

If the distance between the viewing platform and the accommodation areais large, an elevator can be provided inside the tower to save time whenmaking several trips a day between the viewing platform and theaccommodation area, on the one hand, and to limit the physical burden onthe personnel, on the other hand. The elevator can be equipped with anemergency telephone facility so that help can be called in the event ofthe elevator breaking down.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a first embodiment of the cable system on a wind farm;

FIG. 2 a second embodiment of the cable system on a wind farm;

FIG. 3 a third embodiment of the cable system on a wind farm;

FIG. 4 the path of the cable connection between two wind turbines;

FIG. 5 an alternative cable arrangement;

FIG. 6 is an enlarged portion of FIG. 5 showing a suspension and driveof the gondola by means of a main cable and a traction cable;

FIG. 7 a plan view of a wind turbine tower with a protective roof forthe gondola; and

FIG. 8 a side elevation view of the tower with the protective roof fromFIG. 7.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a wind farm comprising nine wind turbines 12. Said windturbines 12 are arranged in three rows, each comprising three windturbines 12 and connected with each other by a cable connection 10 insuch a way that the gondola 14 can reach the separate wind turbines 12separately and consecutively. Thus, when travelling from one end of thecable connection 10 to the other end of the cable connection 10, thegondola 14 always passes all the wind turbines 12 on the wind farm.

The cable connection 10 can be an endless cable loop on which thegondola 14 is fixedly disposed. Therefore, when the cable moves, thegondola 14 is inevitably moved as well.

If the endless cable loop lies in a substantially horizontal plane, thecable can be driven in a constant direction at all times, in thesimplest case, and the gondola 14 moves in the opposite direction afterpassing the deflection point, thereby being shifted by the horizontaldimension of the endless cable loop.

However, since this also applies when travelling from one wind turbine12 to an adjacent wind turbine 12 in the opposite direction, it may benecessary to pass all the other wind turbines of the wind farm such thatthe gondola must travel almost twice the length of the cable connection10.

For example, if the gondola 14 is located at the wind turbine marked Aand must now travel to the wind turbine marked B, it must first travel,in the case of a unidirectional cable drive, to the wind turbine markedC and from there back to the destination wind turbine marked B. In doingso, it travels the entire length of the cable connection almost twice.

If it is possible to drive the cable connection in two directions, allthat is needed for the trip from A to B is a reversal of the directionof travel and a short trip between two wind turbines.

If the cable connection 10 is an endless cable connection in asubstantially vertical plane, a means for driving the cable connection10 in two directions is absolutely essential, since otherwise thegondola fixedly attached to the cable connection 10 would get into ahazardous situation at the latest on reaching the reversal point on theendless cable loop.

For this reason, sensors 44 are provided on the wind turbines marked Band C in the figure, wherein said sensors identify when their positionis reached by the gondola 14, and thus initiate a stop or redirectionprocedure. For the sake of simplicity, these sensors are shown asswitches. Other types of sensor, such as Hall sensors, optical sensors,etc., are also suitable, of course, for determining whether the gondola14 has reached this position. Of course, the position of the sensors ischosen so that there is still sufficient stopping distance even when thegondola 14 is loaded.

FIG. 2 likewise shows a wind farm comprising nine wind turbines 12arranged in three rows each with three wind turbines 12. In thisarrangement, there is a central wind turbine 12 that can have specialdocking and storage facilities, for example. Radiating from this centralwind turbine 12, there is a star-shaped arrangement of cable connections10 connecting to all the other wind turbines 12 of the wind farm. Thisresults in the shortest possible paths for the gondola 14 (not shown inthis figure) to reach the other wind turbines 12—each measured from thecentral wind turbine 12.

However, a trip from one of the non-central wind turbines 12 to anothernon-central wind turbine 12 always leads firstly to the central windturbine 12 and onwards from there to the destination wind turbine 12.

Also shown in this figure is a support mast 11 at a cable connection 10.Said support mast 11 supports the cable connection 10, thus preventingexcessive sag of the cable connection 10 in the case of large spansbetween two wind turbines 12.

This sag results from the cable connection's own weight. Depending onthe properties of the cable connection 10, there is a maximum distancebetween two support points for the cable connection 10, which ifexceeded may result in the cable connection 10 severing under its ownweight. However, even with a lower spacing between the support points,the sag in the cable connection 10 may already be too great, causing thegondola 14 to come too close to the water surface.

This could be counteracted, theoretically, by having a higher tension inthe cable connection 10. However, if a higher tension in the cableconnection arises due to the effect of cold temperatures, the tensilestrength may be exceeded and the cable connection 10 will sever. Inother words, depending on the material used, a certain amount of sag inthe cable connection 10 is unavoidable. However, these problems can besolved by using support masts 11.

FIG. 3 shows the same arrangement of wind turbines 12 as in FIGS. 1 and2. The difference again consists in the structure of the cableconnection 10 between the wind turbines 12. In FIG. 3, the structure islike that of a network, such that each wind turbine 12 forms a node inthe network. By means of this cable structure, even shorter distancesensue for particular stretches over which the gondola 14 (not shown inthe figure) can reach particular wind turbines 12.

In this figure, too, a support mast 11 is provided for a large spanbetween two wind turbines 12 in order to limit the sag and the tensionin the cable connection 10. Of course, support masts 11 can be used inany segment of the cable connection 10 between two wind turbines 12, inorder to gain additional support points for the cable connection 10.

FIG. 4 shows two wind turbines 12 that are connected with each other bya cable connection 10. The upper portions of the towers have been leftout in the figure, although the lower edge of the area swept by therotors is shown by a broken line 30. Each of the towers has an opening18 that can be closed with a door, and from each opening a ladder 32 isprovided that leads to the base of the tower. The opening 18 in thetower is provided at the height at which the gondola 14 reaches thetower.

Above the opening 18 on each tower, a deflection member 16 is providedthrough which the cable connection 10 is guided. The gondola 14 islocated on said cable connection 10. Depending on the embodiment of thecable connection 10, the gondola 14 is carried and/or driven by thecable connection, or the gondola 14 moves under its own power along thecable connection 10.

In the example shown, a drive motor 15 is located on the tower of a windturbine above the deflection pulley 16, said drive motor being able todrive the cable connection 10 in appropriate manner in the case of agondola 14 that is not self-propelled.

In the lower part of the gondola 14 there is an additional compartment26 that is separated from the gondola cabin by the floor of the latter.Inside said compartment 26 there is a flywheel mass 28 which by means ofa drive motor is kept at a high speed of rotation about its rotationalaxis, shown as a broken line. As a result of this rotation, the flywheelmass 28 acts as a gyroscope and stabilizes the gondola 14 in itsposition by counteracting any horizontal displacement on the part of thegondola 14. By this means, the gondola 14 is stabilized while travellingand displaced to only a limited extent, even when cross winds occur.

The drawing in FIG. 5 likewise shows two towers of wind turbines 12, theupper portions of which have been omitted from the figure. However, thelower portion of the area swept by the rotors is again shown. In thetowers, the closeable openings 18 are shown at the height at which thegondola reaches the wind turbine 12.

Above the opening 18 there are deflection members 16 through which thecable connection 10 is guided. The gondola 14 is disposed on said cableconnection 10 and can be made to travel between the wind turbines.

Deflection members 16 are also provided below the openings 18. By meansof these additional deflection members 16, a further cable connection inthe form of a holding cable 24 is guided. Said holding cable 24 runs ata predefined vertical distance 25 parallel to the cable connection 10and guides the gondola 14. By this means, the horizontal excursion ofthe gondola 14 is limited, because it is guided both above and below bycables 10, 24.

The potential horizontal displacement of the gondola 14 varies accordingto the distance to the next wind turbine 12. When the distance betweengondola 14 and wind turbine 12 decreases, the stabilising effect ofdeflection members 16 increases, and the potential horizontaldisplacement of the gondola 14 is accordingly lower, whereas when thedistance between the gondola 14 and a wind turbine 12 increases, theamount of sag in the cable connection 10 and the holding cable 24increases. In the middle of the stretch between two wind turbines 12,the sag is at its greatest, and hence the potential horizontaldisplacement of the gondola 14 is at its maximum.

FIG. 6 shows an enlarged view of the portions enclosed by a brokencircular line in FIG. 4 and FIG. 5. The cable connection 10 is formed bytwo cables 20, 22. The upper cable 20 is provided as a main cable andcarries the gondola 14 which is moveably disposed thereon with two guidesheaves 46. The lower cable 22 is a traction cable and is fixedlyattached to the gondola 14. By operating said traction cable 22, thegondola 14 can be moved in a suspended position along the main cable.

FIGS. 7 and 8 show a wind turbine 12 (FIG. 7) and a portion of the towerof the wind turbine 12 (FIG. 8) with a cover 34 of substantiallyhorizontal extension disposed thereon. FIG. 7 is a plan view and FIG. 8a side elevation view.

The cable connection 10 runs below said cover 34; the means by which itis suspended is not shown here for the sake of a better overview.Protective walls 36 are disposed on each of the two sides of the cover34 that run parallel to the cable connection 10.

In combination with the cover 34, these protective walls 36 form aprotective roof that protects the gondola 14 and the opening 18 in thetower of the wind turbine 12 against the weather. Said protective roofextends on both sides of the opening 18, parallel to the cableconnection 10.

The outer ends of the protective roof are widened, due to the fact that,while the gondola is travelling between two wind turbines 12, horizontaldisplacement of the gondola 14 is possible at all times, albeit limitedin amount and direction. The spacing between the protective walls 36increases in predefined portions of the protective roof with increasingdistance from the opening 18. In the middle portion, near the opening18, the dimensions of the protective roof can be substantially equal tothose of the gondola 14.

By means of the greater spacing between the protective walls 36, thegondola 14 can be moved between the protective walls and hence intotheir lee side, even when, for example, the gondola is horizontallydisplaced by cross winds. Owing to the shelter from the wind thusprovided, the gondola 14 is no longer displaced and for this reason thespacing between the protective walls 36, 38 can be made smaller.

Elastic coatings 48 are provided on the protective walls 36, 38 in theentry area, said coatings being intended to dampen any collision of thegondola 14 with the protective walls 36, 38 in such a way at least thatno significant damage occurs. Independently of these coatings 48 on theprotective walls 36, 38, similar coatings can be provided on thegondola, for example in the form of fenders.

Another embodiment of a wind farm according to the invention, has anoffshore platform and the wind turbines of the wind farm. For the sakeof simplicity, the cable connection between the wind turbines themselvesare not shown (see FIG. 3 or FIG. 2 instead). There is a cableconnection between the offshore platform and at least one wind turbinethat is centrally allocated in the wind farm to the platform. Anotherpossible configuration (see FIG. 2) is a star-shaped arrangement of thecable connection between the platform and the wind turbines, wherein theplatform then forms the centre of the star-shaped network.

As on previously known offshore oil-drilling platforms, all thefacilities enabling people to stay on the platform for extended periodscan be accommodated on the platform. These include, in particular,living quarters, sleeping quarters, mess rooms and all other facilitiesthat also enable the wind farm maintenance and operating personnel tostay for several weeks at a time.

In addition, the platform itself can be equipped with electrolysisequipment (this can also be provided on a separate platform) so thatwater can be converted electrolytically into its constituent elements,oxygen and hydrogen, using the power generated by the wind turbines ofthe wind farm. Both gases, in any case the hydrogen gas, is then storedin gas tanks provided in the platform or separately thereto, or the gasproduced is conveyed to land by means of pipelines. When the gas isstored on the platforms, it can be collected by suitable transportships.

The special advantage of such hydrogen production is that fluctuatingpower generation due to varying wind conditions is of no concern,because the gas tanks provide an adequate buffer that permits continuoustransportation of gas despite fluctuating production output.

Given that the production of hydrogen from water makes sense only ifrenewable energy is used, a very large production capacity can beprovided with the wind farm, because the electrical power output of thewind farm is in the order of several megawatts, and preferably in excessof 500 MW.

The platforms themselves are also so large, generally, that they arefitted with a special helicopter landing pad, such that people can betransported to the wind farm by helicopter and that the helicopters canland relatively safely on the platforms on account of their substantialsize.

The cableway connection of the invention between the platforms and atleast one wind turbine also has the advantage that, in the event of anaccident on the residential platform, the personnel can still move tothe wind turbine, where it is firstly in safety.

In order to avoid any collision between passing ships and the gondola,the gondolas and/or the cables are also fitted with an anti-collisionlight that is switched on unavoidably on at least one moving gondola,thus attracting a very high level of attention on the part of anypassing ships.

It is also possible to provide technical facilities that permit the gapbetween the gondola and an obstruction to be detected, i.e., using radaror ultrasound.

In order to receive a certain advance warning, the boundaries of thewind farm or sections of the wind farm, for example, can also bemonitored for entry of a watercraft. This can be effected with visualmonitoring means, or with radar equipment or the like. In combinationwith such a means, a forced control can be activated when a ship isdetected entering the wind farm, wherein said control forces thegondolas to travel to the nearest wind turbine, so that any collisioncan be safety prevented. At the same time, standard warning messages canbe transmitted to the ship's bridge over certain radio channels, such asthe emergency channel, warning them of the hazard.

In order to help sailors or water sportspeople after an accident at seausing the gondolas, the gondolas can also be equipped with safetyequipment such as jack ladders, winches for rescue seats or the like,and first-aid equipment or similar.

The platform can also be a life-saver for people shipwrecked in the areaof the wind farm, in particular when an injured or freezing person onthe high seas can be taken care of on the platform to such an extentthat initial recovery can occur. It is advantageous in this context ifthere is basic medical equipment and supplies on the platform, so thatprimary or minimum medical treatment can be assured.

From the foregoing it will be appreciated that, although specificembodiments of the invention have been described herein for purposes ofillustration, various modifications may be made without deviating fromthe spirit and scope of the invention.

1. An offshore wind farm comprisign: at least one offshore platformwithin the wind farm, said platform being suitable for providing theliving and accommodation space for the personnel operating the windfarm; a cable connection being provided between said platform and atleast one wind turbine of the wind farm; and a gondola hanging on saidcable connection for travelling from said platform to said wind turbine.2. The wind farm according to claim 1, characterized in that a spareparts depot for the most important wearing parts of the wind turbine isprovided on the offshore platform and that said parts are transported tothe wind turbines via the cableway connection.
 3. The wind farmaccording to claim 1, characterized in that the platform is equippedwith an electrolysis plant that is supplied with electrical power by thewind turbines, wherein hydrogen and oxygen are produced from water bymeans of electrolysis.
 4. The wind farm according to claim 3,characterized in that the offshore platform has one or more gas tanks inwhich the gas produced (H₂; O₂) is stored.
 5. The wind farm according toclaim 1, characterized by at least two wind turbines and a cableconnection spanning at least two wind turbines at a predeterminedheight, and a gondola disposed on said cable connection.
 6. The windfarm according to claim 5, characterized by a cable connection spannedas an endless cable between deflection members at the wind turbinesand/or the platform and by a rigid connection between the cableconnection and the gondola.
 7. The wind farm according to claim 5,characterized by a cable connection comprising a main cable and atraction cable and a gondola, the gondola being moveably connected tothe main cable and fixedly connected to the traction cable.
 8. The windfarm according to claim 7, characterized by a traction cable extendingas an endless loop along the deflection members.
 9. The wind farmaccording to claim 7, characterized by a deflection member with twoindependently rotatable deflection pulleys.
 10. The wind farm accordingto claim 7, characterized by the traction cable being driven by a motor.11. The wind farm according to claim 5, characterized by a gondola thatmoves along the cable connection under its own power.
 12. The wind farmaccording to claim 11, characterized by at least one motoric drive formoving the gondola along the cable connection, wherein the drive ispreferably an electrical drive.
 13. The wind farm according to claim 12,characterized by the gondola drive receiving a drive power supply from astore of energy carried in the gondola.
 14. The wind farm according toclaim 11, characterized by at least one manually operable drive formoving the gondola along the cable connection.
 15. The wind farmaccording to claim 11, characterized by a remotely controllable drivefor moving the gondola.
 16. The wind farm according to claim 15,characterized by use of at least one portion of the cable connection asan electrical conductor.
 17. The wind farm according to claim 16,characterized by a cable which is integrated into the cable connection.18. The wind farm according to claim 5, characterized by a star-shapedarrangement of cable connections between a specified wind turbine andthe other wind turbines.
 19. The wind farm according to claim 5,characterized by a networked arrangement of cable connections betweenthe wind turbines, wherein each wind turbine forms a node in thenetwork.
 20. The wind farm according to claim 5, characterized by asingle cable connection between the wind turbines of the wind farm, saidcable connection connecting at least one portion of the wind turbines ina predeterminable sequence.
 21. The wind farm according to claim 18,characterized by a combination of at least two of the aforesaid systemsof cable connections.
 22. The wind farm according to claim 1,characterized by a detachable locking device between the gondola and thetower of a wind turbine.
 23. The wind farm according to claim 22,characterized by a locking device in the form of a holding magnet. 24.The wind farm according to claim 1, characterized by a holding cableextending parallel to the cable connection at a predefined distancetherefrom.
 25. The wind farm according to claim 1, characterized by acable connection extending at a predefined horizontal distance from thetower of the wind turbine, and/or by a holding cable extending at apredefined horizontal distance from the tower.
 26. The wind farmaccording to claim 24, characterized by deflection members on the windturbines for accommodating the holding cable.
 27. The wind farmaccording to claim 24, characterized in that the cable connection isconfigured as an endless cable loop, and that the holding cable is partof said endless cable loop.
 28. The wind farm according to claim 1,characterized by a gondola with a flywheel mass rotating about avertical axis.
 29. The wind farm according to claim 1, characterized bya closeable opening in the tower of a wind turbine at the height atwhich the gondola reaches the tower.
 30. The wind farm according toclaim 29, characterized by a locking device at the height of the gondolanear the opening.
 31. The wind farm according to claim 1, characterizedby a cover of substantially horizontal extension disposed above theopening on the tower of at least one wind turbine.
 32. The wind farmaccording to claim 31, characterized by a first protective wall disposedon the side of the cover facing away from the tower, said protectivewall extending substantially vertically and at a predefined distanceparallel to the cable connection.
 33. The wind farm according to claim1, characterized by at least one second protective wall disposed at thetower of the wind turbine at the height of the opening and extendingsubstantially parallel to the cable connection.
 34. The wind farmaccording to claim 33, characterized by a two-part second protectivewall extending a predefined length on both sides of the opening.
 35. Thewind farm according to claim 32, characterized by a gap between thefirst protective wall and the second protective wall, said gapincreasing in size in a predefined portion at a distance from theopening.
 36. The wind farm according to claim 32, characterized by anelastic coating of predefined thickness on at least one of theprotective walls.
 37. The wind farm according to claim 31, characterizedby at least one lighting installation on the cover and/or the protectivewalls.
 38. The wind farm according to claim 1, characterized by at leastone gangboard extending substantially parallel to the cable connection,said gangboard being reachable from the opening and having at least oneretention facility along its entire length.
 39. The wind farm accordingto claim 1, characterized by a single- or multi-part working platform onthe outside of the tower of at least one wind turbine, wherein saidplatform can be reached from the opening.
 40. The wind farm according toclaim 1, characterized by a crown safety platform or a working cageoutside the tower of at least one wind turbine, wherein said platform orcage can be reached from the opening.
 41. The wind farm according toclaim 1, characterized by at least one first guide rail disposed on thetower of the wind turbine close to the opening and extendingsubstantially parallel to the cable connection.
 42. The wind farmaccording to claim 41, characterized by a second guide rail extending ata predefined distance substantially parallel to the first guide rail.43. The wind farm according to claim 41, characterized by a gap betweenthe first guide rail and the second guide rail, said gap increasing insize in a predefined portion at a distance from the opening.
 44. Thewind farm according to claim 41, characterized in that the guide railssupport the protective walls.
 45. The wind farm according to claim 29,characterized in that the closeable opening is larger than the gondolaand the cable connection extends through the opening into the inside ofthe tower of the wind turbine.
 46. The wind farm according to claim 1,characterized by at least one set of points at each tower along thecable connection.
 47. The wind farm according to claim 1, characterizedby load anchoring facilities and lashing means in the gondola.
 48. Thewind farm according to claim 1, characterized by a hoisting devicelocated on or in the gondola for handling the load being carried. 49.The wind farm according to claim 1, characterized by a hoisting and/ortransportation apparatus at or in the tower of at least one windturbine.
 50. The wind farm according to claim 1, characterized by agondola with an enclosed gondola cabin.
 51. The wind farm according toclaim 1, characterized by an elastic coating at at least one location onthe gondola where the risk of collision with other wind farm facilitiesis greatest.
 52. The wind farm according to claim 1, characterized by abuoyant gondola.
 53. The wind farm according to claim 1, characterizedin that the elastic coating serves simultaneously as a float.
 54. Thewind farm according to claim 1, characterized by a control devicecomprising a central control unit, sensors and/or actuators.
 55. Thewind farm according to claim 54, characterized by the central controlunit being disposed in one of the wind turbines of the wind farm. 56.The wind farm according to claim 54, characterized by at least onesensor that detects when the gondola passes by.
 57. The wind farmaccording to claim 1, characterized by a GPS module disposed in thegondola.
 58. The wind farm according to claim 1, characterized in thatelectrical energy generated in the wind farm is used to power theelectrical drives.
 59. The wind farm according to claim 58,characterized in that the energy is selectively drawn at the generator,at an intermediate DC circuit or at some other suitable point.
 60. Thewind farm according to claim 1, characterized in that energy istransported within the wind farm at least partially in a form other thanelectricity.
 61. The wind farm according to claim 1, characterized bymasts disposed adjacently between the towers of the wind turbines forsupporting the cable connection.
 62. A method for controlling the cablecar system provided between at least two wind turbines of a wind farm,characterized by evaluation by the central control unit of the situationas detected by the sensors, and the triggering of appropriate controlsignals for the actuators.
 63. The method according to claim 62,characterized by the transmission to the central control unit of GPSdata and/or data in other encoded form indicating the position of thegondola.
 64. The wind farm according to claim 1, characterized by leastone wind turbine having an accommodation area for accommodating at leastone person.
 65. The wind farm according to claim 64, characterized bythe accommodation area being equipped with a sanitary area and/or akitchen area and/or a pantry area and/or a rest area.
 66. The wind farmaccording to claim 64, characterized by the accommodation area beingintegrated in the tower of a wind turbine.
 67. The wind farm accordingto claim 64, characterized by the accommodation area being arranged in aplurality of interconnected levels.
 68. The wind farm according to claim64, characterized by a device for signalling predefined data and/or adevice for influencing predefined operating parameters within theaccommodation area.
 69. The wind farm according to claim 64,characterized by a communications facility for exchanging informationand/or data.
 70. The wind farm according to claim 64, characterized by awater treatment plant for supplying the personnel with drinking waterand service water.
 71. The wind farm according to claim 64,characterized by characterized by energy storage means for storingenergy to bridge gaps in power supply.
 72. The wind farm according toclaim 64, characterized by devices for weather observation, and/or fordetecting, analysing, recording and/or forwarding meteorological data.73. The wind farm according to claim 64, characterized in that at leastthe wind turbine with the accommodation area has navigational aids forshipping and/or equipment for helping injured or shipwrecked persons.74. The wind farm according to claim 64, characterized by a viewingplatform on the tower of the wind turbine in which the accommodationarea is located, said viewing platform encircling the tower below themachine house either completely, or at least partially in a preferreddirection.
 75. The wind farm according to claim 74, characterized inthat at least part of the viewing platform has windows to enable thesurroundings of the wind turbine to be monitored.
 76. The wind farmaccording to claim 74, characterized by an elevator between theaccommodation area and the viewing platform.
 77. The wind farm accordingto claim 64, characterized in that the platform is a discarded/used oilor gas drilling platform.